Diseases of the Colon & Rectum Translumbar and Transsacral Magnetic Neuro-Stimulation for the Assessment of Neuropathy in Fecal Incontinence --Manuscript Draft-Manuscript Number:

DCR-D-13-00433R3

Full Title:

Translumbar and Transsacral Magnetic Neuro-Stimulation for the Assessment of Neuropathy in Fecal Incontinence

Short Title:

Neuro-stimulation in fecal incontinence

Article Type:

Original Contribution

Corresponding Author:

Satish S. C. Rao, MD, PhD Georgia Regents University Augusta, Georgia UNITED STATES

Corresponding Author Secondary Information: Corresponding Author's Institution:

Georgia Regents University

Corresponding Author's Secondary Institution: First Author:

Satish S. C. Rao, MD, PhD

First Author Secondary Information: Order of Authors:

Satish S. C. Rao, MD, PhD Enrique Coss-Adame, MD Kasaya Tantiphlachiva, MD Ashok Attaluri, MD Jose Remes-Troche, MD

Order of Authors Secondary Information: Manuscript Region of Origin:

UNITED STATES

Abstract:

Background: Neurological dysfunction causes fecal incontinence, but current techniques for its assessment are limited and controversial. Objective: To investigate spino-rectal and spino-anal motor evoked potentials simultaneously using lumbar and sacral magnetic stimulation in fecal incontinence and healthy subjects, and to compare motor evoked potentials and pudendal nerve terminal motor latency in fecal incontinence subjects. Design: Prospective observational study. Settings: Two Tertiary Care Centers. Patients: Adult fecal incontinence and healthy subjects. Interventions: Translumbar and transsacral magnetic stimulations performed bilaterally by applying a magnetic coil to the lumbar and sacral regions in 50 fecal incontinence (≥ 1 episode/week) and 20 healthy subjects. Both motor evoked potentials and pudendal nerve terminal motor latency were assessed in 30 fecal incontinence patients. Stimulation-induced motor evoked potentials were recorded simultaneously from rectum and anus with two pairs of bipolar ring electrodes. Main Outcome Measurements: Latency and amplitude of motor evoked potentials after lumbosacral magnetic stimulation and agreement with pudendal nerve terminal motor latency. Results: When compared to controls, one or more lumbo-anal, lumbo-rectal, sacroanal, or sacro-rectal motor evoked potentials were significantly prolonged (p4.0 ms for translumbar-rectal MEP, > 4.2 for translumbar-anal MEP, > 4.1 for transsacral-rectal MEP, and > 4.5 for transsacral-anal MEP; and for PNTML, an onset time of > 2.2 ms26. A p value < 0.05 was considered statistically significant.

The primary comparisons between the FI patients and healthy controls were the MEP data. Additional comparisons were made between the MEP responses and the PNTML responses in FI patients and in healthy subjects by using MannWhitney U-test. Differences in the prevalence of abnormal test between MEP or PNTML test were compared by using X2. The mean differences for the anal

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sphincter pressures, and for the rectal sensory thresholds and for the balloon expulsion tests between the two groups were compared using Student’s t -test. Incontinent subjects were considered to have rectal hypersensitivity when two or more of the three rectal sensory threshold volumes (first sensation, desire to defecate, urgency to defecate) were lower than 2 S.D. of the normal mean value, and rectal hyposensitivity when rectal sensory thresholds were higher than 2 s.d. of the normal mean values23, 27.

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RESULTS

Subjects

Fifty patients with FI, F/M = 42/8, mean age 61(31-87) years, and 20 healthy subjects (F/M = 10/10, mean age 40 (21-59) years (p= 0.001) were enrolled. Also, 34/50 FI patients (F/M = 31/3, mean age 62±12 years) and 15/20 (F/M = 9/6) healthy controls underwent the PNTML test. Four out of 34 patients were excluded from the comparative analysis because of technical failure to obtain PNTML in (3 patients), and MEPs (1 patient).

Demographics/Baseline Anorectal function tests

Seven patients (14 %) had diabetes mellitus and 8 (16%) had previous anorectal or transperineal surgery, and 4/42 were nulliparous. The median number of pregnancies in the multiparous women was 3 (range 2-10) while the median number of pregnancies in HC was 1 (range 1-4) (p= 0.0001). All FI patients had vaginal delivery, and twelve reported a history of difficult labor (large baby, instrumentation, or breech). All HC had vaginal deliveries, and 2 also had Csection. There were 5 HC that reported vaginal tears and 2 had difficult labor that required using forceps. Thirty six patients had urge incontinence, 9 had passive incontinence and 5 had fecal seepage. The mean Vaizey score (0-24) was 15 (range 4-22). There were 28 patients with leakage of solid stools, 36 liquid stools and 34 with gas incontinence. Majority of patients had a mixed pattern of 12

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incontinence with significant overlap. The median number of FI episodes/week was 1. Ten (20%) had coexisting urinary incontinence. The results of anorectal manometry and rectal sensation are shown in table 3. Resting and squeeze sphincter pressures and squeeze duration were significantly decreased (p